Regarding microwave transceiver apparatuses using a phased array antenna device, transmitters are not required to have linearity when used for radar purposes but are required to have linearity when used for communication purposes.
In microwave transceiver apparatuses using a phased array antenna device, it is required to downsize a transceiver module connected to each element antenna. Therefore, there is necessary to raise efficiency of a power amplifier included in a transceiver.
However, raising efficiency of a power amplifier generally results in larger nonlinearity, and as a result, distortion occurs.
Patent Literature 1 listed below discloses a technique for enhancing linearity of a microwave transceiver apparatus using a phased array antenna device.
That is, Patent Literature 1 discloses a technique for enhancing linearity of a microwave transceiver apparatus using a phased array antenna device by transmitting a microwave that is a transmission signal, then collecting a reception signal of the microwave as a feedback signal from a receiving terminal receiving the microwave, and performing distortion compensation processing on a transmission signal using the feedback signal.
Patent Literatures 2 to 6 listed below disclose techniques for enhancing linearity of an antenna module forming a phased array antenna device.
That is, Patent Literatures 2 and 4 disclose techniques for enhancing linearity of each antenna module by switching switches connected to each antenna module, thereby returning a signal transmitted from each antenna module as a feedback signal, and performing distortion compensation processing on a transmission signal using the feedback signal for each antenna module.
Patent Literature 3 discloses a technique for distributing a transmission signal after distortion compensation processing to a plurality of antenna modules by performing the distortion compensation processing of adding an opposite distortion signal to the transmission signal by a synthesizer in an RF unit assuming that operations of all antenna modules forming a phased array antenna device have the same characteristics.
Patent Literature 5 discloses a technique for enhancing linearity of each antenna module by extracting a part of signals transmitted from each antenna module as a feedback signal by a distributor connected to each antenna module and performing distortion compensation processing on a transmission signal using the feedback signal for each antenna module.
Patent Literature 6 discloses a technique in which a distortion compensation device is mounted on a part of a plurality of antenna modules forming a phased array antenna device.